Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a first image in a sequence for a display screen or portion thereof with transitional graphical user interface, showing my new design;

FIG. 2 is a front view of a second image thereof;

FIG. 3 is a front view of a third image thereof;

FIG. 4 is a front view of the display screen or portion thereof with transitional graphical user interface of FIG. 1 in which a device is provided in broken lines to illustrate an example environment;

FIG. 5 is a front view of a second image thereof; and,

FIG. 6 is a front view of a third image thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1 through 3 and FIGS. 4 through 6. The subject matter of this patent includes a process or period in which an image changes into another image. This process or period forms no part of the claimed design.

The broken line showing of the device, and the symbol and other images is included for the purpose of illustrating environmental structure and portions of the article, respectively, and forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 